Boiler and method of operating the same



EJZZASS July 30, i929a w. B. CHAPMAN BOILER AND METHOD OF OPRATING THE SAME ssneets-sneet 1 Filed July 29, 1926 July 30, 1929. W, B CHAPMAN l 1,722,496

BILER AND METHOD OF OPERATING THE SAME Filed July 29, 1926 3 Sheets-Sheet 2 @AAM July 30, 1929. W. B. CHAPMAN BOILER -AND METHOD OF OPERATING THE SAME Filed July 29, 1926 5 Sheets-Sheet lill' INV NTOR Q. @d Pm-jf ma Dm ATTORNEYS .Patented .my 30, 1929-VA wmLim B. CHAPMAN, oir JACKSON HEIGHTS, Nnw vom;

B oILEn. .um iii-Emisiones" OPERATING'TBE SAME.

Application viiieiiiiiiiy 29, 192e. serial NQ. 125,6a2.

The invention in one of its aspects relates to a boiler designed paiticularly to be heated by the use of fine sizes of coal without, however, requiring that the coal be first subjected to pulverizing operations to reduce it to an W exceedingly fine and uniform size.

The invention aims to provide finely divided coal will be afforded a relatively long path of travel within the range of the heat exchange surfaces, and durin which path of travel such currents Willl be rought v into efficient contact with the boiler tubes, the

coal particles which do not burn in suspen- `sion being collected in a fire bed which is convditoned and regulated as hereinafter specifie v `Another object of the invention is tofproregard to the tubes to be heated, in their iiow y through'the boiler, thereby promoting univv for'inity vof the heating action and avoiding local dead pockets, stream lines and the usual irregularity of heat distribution found ini boilers of the conventional type. a

According to the above features of the present invention fine sizes of coal are fed through the combustion chamber of a-boiler in such y v30,` manner that a large portion 0f the fuel par-' ticles is burned in suspension, the remaining particles dropping onto a re bed which is maintained so deep that a certain amount of producer gas is generated', the producer gas .o .thus formed being'led past the boiler heat interchange surfaces and being mixed with the amount of air necessary to complete its combustion, the gases of combustion then reversing their directionto pass again along theheat aI boilei` Y 7 wherein gaseous currents carrying suspended `2--2 of Fig. 1.

43--2 of Fig. 2.

interchange surfaces and the last pass being preferable in a downward direction whereby of their heat and hence have be-v In accordance with another 'feature of the holes, breaking up clinkers, and the lash is rc-` the gas production makes it possible to` su ply secondary air in such quantities as wil bev proper to complete its combustion, avoiding the inefficiency which arises out of the excess of air usually employed for combustion purposes.

The above features of the invention ma be conjointly used if desired, small fuel particles being consumed in suspensionand yproducer gas being generated from the larger sizes as above described, and mixed with secondary -air to assist inbiirning the suspended parti- Further ob'ects and advantages of the invention will e in part obvious and `in part specifically pointed Aoutin the descriptionv hereinafter contained which taken in convjunctionwith the accompanying drawings vide a boiler wherein the heating gaseous curv 20 -rents will be substantially.symmetrical with discloses certain boiler constructions adapted lto be operated in accordancel with the invenboiler adapted to operate in accordance with the invention. a Fig. 2 is a transverse section taken on line Fig. 3 is a detailed section taken von linel Fig. 4 is a view similar to Fig. 1 but showingra modied boiler construction.v i f ig. 5 is a horizontal section taken on line 5-5 of Fig. ,4. In the embodiment of the invention illustrated in Figs. 1 to 3 I have shown a boiler having an upright substantially cylindrical .combustion chamber 1 surrounded by concentric annular sets of water tubes 2 and 3 which are :joined at their bottoms to an annularfheader 4 su ported by suitable masonr work, said tubes liaving bent portions whic are joined to an u per header or drum which overlies the com ustion chamber 1.y

The lower header 4 surrounds the fire bed shown in Fig. 1 as supported by a grate denoted generall by numeralG, t e fuel being` fed in by suitable mechanism (not illustrated) through a central openin 7 in the tolp wall of the boiler,from whence t e fuel fal s axially ,down toward the fire bed supported by grate 6.

As above stated, the fire bed is maintained ioo at a jsutcient depth to generate carbon one foot up to several feet in depth, instead of several inches, as is customary, and a fire bed agitating member 8 shown as extending substantially diametrically across the lire bed immediately above grate 6, is slowly turned also serves to grind up clinkers in the bottom of the fire bed to sizes sufficiently small to pass through the openings in grate 6 and sweeps the grate clean, being located just above it.

The grate 6 furthermore is so constructed as to enable the effective size of its openings as regards ash removal to be adjusted whereby the beam 8 may be operated at theproper uniform speed to maintain uniform conditions of combustion within the fire bed, and the grate 6 adjusted to permit ash to drop through substantially at the rate of ash production, thus maintaining a fire bed'of uniform depth and other characteristics which will produce the grade of gas essential to efficient operation.

A s shown the grate 6 consists of an upper l fixed section 9 having arcuate grate openings 10 therein and a plurality of sector shaped lower sections 11 slidablysupported on ledges 12 (Fig. 3) and having arcuate grate openings 13, thus permitting the lower grate sections 11 to be moved back and forth radially to place the grate openings 13 more or less in alinement with openings 10. The

. igratefsections 9 and 11, however, are sufciently spaced to permit a substantially'un# impeded flow of the blast through lthe fire bed, the blast being shown i'n Figfl as passing into a chamber 14 beneath the grate through a pipe 15.

. -The agitatin member 8 in the form of the inventioni' lustrated in Fig. 1 .is supported upon a hollow post 16 passing down through a central opening in the ate and 'supported upon a rotaryc table 17 which is drlven by suitable gearlng which need not be described in detail. The table 17 also receives the ash dropping down through the grate and carries it around until pushed oA by a stationary sweep 18, which pushes the ash olf into an ash water-sealed. i. In case coarse sizes of fuel areem loyed, the coal may be merely dropped. in tlirough the opening 7, or in case finer sizes are employedthe coal may be fed in through an air spout directed centrally through" the opening 7, the lower header 4 being pro- -bodily with the agitator. lIn either case .a

,I venting the centralstream of Coldfuel from p1t 19 which is shown as vided with inclined ridges 4c which assist in grinding up the ash andf--preventing--the' ebed as' a whole froml turning. around central stream of fuel will pass downwardly t through the combustion chamber 1, as illus'- trated in Fig. 1, the heavienfuel'particles falling onto the fire bedand the producer. gas which is formed in theA fire bed will rise- 1nv an annular `stream passing upwardly` 7. along the vheat interchange surfaces of water tubes2. Some of theV finer fuel particles passing in through opening 7 will be-consumed beforereaching the fire bed, thus precooling the boiler. y i

The producer' gas formed as above describedl is mixed with secondary air and its combustion thereby completed, the secondary air being shown in Fig. 1 as su plied through a series of `pipes 20 passing 1n through the walls of the boiler to points in combustion chamber 1, somewhat above the top'level of the fire bed. The jets of air thus supplied form a stratum of air acros'sthe producer just above the firebed, through which the producer gas must pass soon after leaving the firebed. These pipes preferably are directed tangentially, as shown in lig 2, in order to impart a whirling motion to thevrising `annular column of burning gases, thereby serving to direct the gases outwardly against. tubes 2 and avoid unbalanced conditions in differenty zones of combustion chamber' 1.

After passing spirally upwardly to the top of combustion chamber 1 the gases of combustion turn and pass in a slightly spiral downward direction through an annular passageway "21 between tubes 2 and 3. As shown special bricks 22 are interposed be- 105 tween adjacent tubes 2 in order to form a partition between the passageway 21 and the combustion chamber, which partition extends nearly to the tops of the tubes. After passing downwardly through passageway 21 110 A as above described, the spent gases may be collected in an annular gathering chamber 23 surrounding lower header 4 (except at the point where ash pit 19 is located) suit able ports 24 with dampers 25 being pref- 115 erably interposed between the passageway and the gathering chamber in order to enable -the draft ,to` be balanced aroundl the boiler, by adjustment of the several dampers. The spent gases maypthen pass out through 1z0 an exhaust flue 26.

t In the operation of the boiler fuel will be fed in ,according to the rate ofconsumption desired, and the speed of rotation of the agi tating member8 so adjusted as to level the 125 tained of unifoin" thickess and waauni;

, form conditionsof rcombustion therein,

' kwhich will 'enable gas A'of uniform quantity and quality toebe' producedl This makes it possible to feed in amounts of airthrough pipe which will'be correct for completing combustion of the producer gas. The hot gaseous currentsv thenwill pass twice past up the greater proportionof'their heat willA the heat interchange surfaces of the boiler and since the last pass is in a downward direction only those gases which have given pass down to gathering chamber 23. vThe lower header 4 serves ,the Vdouble purpose of affording extra heat interchange area, and

providing water cooled -w'al'ls for the fire bedl which prevent the undue building up ofl slag de osits upon such walls.

he invention is illustrated in 4 and 5 as applied to a boiler having an upright substantially cylindrical.' combustion* chamber 1a surrounded by a single annular set of boiler tubes 2' which are joined at their bottomsv to an annular header 3L suitably sup'- ported by masonry work, and said tubes hav- -inginwardly bent' tops which are joined to an upper header or drum 4* which overlies the combustion chamber 1. This drum 4 may be provided with a manhole 5 through which all of the tubes are accessible for cleaning purposes. Y

In th's form of the invention the heating gaseous currents pass twice through the comv bustion chamber l, one of the passes consistlng of' a central longitudinal stream and the ot1er`consisting of an annular gaseous current or. stream which 'encloses the central stream above mentioned and furthermore is refer-ably caused to follow 'a helical or whirlf mg path as it'travels througlLthe combustion chamber.

.Asv shown, the' combustion chamber 1B. is

l provided with downwardly convergingbottom walls 6. which will form a restricted throat at the'bottom ofthe combustion chamber and a restricted bottom opening 7,

through which the air for combustion is projected in an upwardly moving stream issuing from pipe 8, In the present embodiment finely divided coal 'isalso 'fed in through pipe 8, and the central .stream above mentioned travels u wardly to the top of the' vcombustion'cham er with a suicient velocity toa uniform powdered condition. Although -powderedcoal ofcourse may be used,if desired, the boiler lwill operate satisfactorily to float and carry along most of the fuel particles even though the latter be not reduced with coalwhich has been crushed merely to pass through a 5 or'10 mesh screen. Coal of 'this' fneness does not require a pulveriz'er for its preparation and is therefore much less expensive thanpowdered coal.'- p Y After reachingthetop of combustion chamber l the stream is reversed in direction `conform to the natural tendency of hot and travels downwardly in an annular stream or current next to the boiler tubes 2a andI prefer, furthermore, to impart a whirling or helical motion to this annular current as it passes downwardly. As shown secondary air 1s fed 1n at the top of the combustion chamber by means of a series-of pipes or nozzles v 9a which are directed tangentially of thev com'-l bustion chamber, and therefore set upa vor., v, l

tex in the top of the chamber which .causes the downwardly moving column of air Aand suspended fuel to whirl in a transverse plane out against the tubes 2, while the descending ,o

column ofburned gases is finally' carried so `outvthroughv one or more exhaust 'openings'.

10 disposed around the bottom ofthe com-l bustion chamber 1a and leading toan; annular chamber '11, from which the spent gases finally pass downwardly through a suitable number of ports 12 spaced laround chamber 11 and leading toy the exhausty iue'la.

.If desired', further semi-circular' boiler tubes ing column of gas and fuel,.however, gives up its heat to the tubes both by radiation and by direct contact therewith, land ywith the elliclency of the heat exchange action being ylargely increased, both due to the Afactthat the gases are swept or whirled outwardly directly against the tubes and the lfact that their path of travel in range of the ,tubesl is greatly increased due to the whirl. The path of travel of the 4hot gases through the combustion chamber is such that -the lrise as they take on heat and fall as they give up heat, whereby'only the' cold gases, which accordingly have given up the majorportion of their heat, will be exhausted from the combustion chamber; thus the path of the gases to rise and cooling gases to fall.--

yIt wi11fuaher be noted that the path ofV thel gaseous streamsand the travel ofthe ases is symmetrical with regard to the heat-` ing surfaces of the boiler, that isA to say, the, central rising stream of 'air and suspended fuel is substantially equisdistant from all' tubes, while the whirling downwardly moving column of gas and fuel-is concentric with the annularset of tubes. The hot gases there-l fore tend to heat all ofthe tubes alike and l there is little` or no tendency toward the.for'

mation of local hot or cold spots in the boiler.

The symmetrical travel -ofl the vgases is maintained in leading them from the combustion chamber, the openings 10 perm-ittlng the gases to. pass substantially uniformly into chamber 11a, from all lpoints around the bottom. of the combustionchamber, while damp.` .f f

ers Iassociatd'with the ports 12a may be ad] ustedLyto produce uniform flow downward from chanibcr' 118L to'th'e exhaust flue 13, at

differentpoiiits' "around the periphery of chamber' 10,11.

A-si's shown moreclezfrl'yfin Fig. 5, the

tubes 2 preferably arealls'pac'ed' from eachv other to some extent arid I prefer to employ in connection with the tubes, a' sheet metal sheathing 17 which has'semi-cylindrical depressions 18n therein -respectively receiving and closely engaging the several tubes. The surfaces .19 of the sheathing which lie between the tubes, are exposed directly to the action of the hot gases and serve to conduct t -further heat to the tubes. These parts 1,9a of the sheathing furthermore are free to buckle more or less which will be desirable in allowing the sheathing to. accommodate itself to temperature changes. As shown in Fig. 5 sections of the sheathing 17 may be welded together to make up a'tight housing for the boiler tubes 2. I

-Such fuel particles as are not carried along and burned withv the Agaseous current, may

` falldownwardly through the bottom opening 7a of the combustion. chamber into an auxiliary chamber 20a provided with a grate 21a which is shownas being rotatable by means of a car 22- associated therewith. l The fire be in chamber 20a operates to form producer gas substantially as previouslydescribed in connection. with Fics. 1 to 3, air under pressure being' su plied through a suitable pipe 23' beneath tie grate and a stationary agitatingmember" 2lia extending radially over',

the grate to agitate'the fire bed. "As the latter rotates with the grate the agitating member 24,- also serves to'eject ash into a' Water-v sealed ash pit 25a. As shown in Fig. 4 the lower walls 6fof combustion chamber 1a are lcooled by air passing into a' chamber 26n which surrounds such walls, such cooling air passing outwardly through a pipe 27 inf velocity of the -stream issuing from pipe 8II from blowing itself'out.

lVhile the invention has been described as applied to certain specific boiler structures,

it will be obvious that many changes may be made therein without departing from its lprinciples as defined in the appended claims.

I claim: 1. The method of operating a boiler having a combustion chamber and'boiler heating surfaces surrounding the same, which comprises projecting a central streamv of finely divided fuel longitudinally through the central portion of said combustion chamber,

defiecting said stream toward the heating surfacesv adjacent-one end of the combustion chamber, andimparting a Iwhirling motion thereto to cause the gases of combustion to travel back through-the combustion chamber in the form of an annular whirling column surrounding said first mentioned stream.

2. The method of operating a boiler having a vertical combustion chamber with boiler heating surfaces surrounding the same, which comprises projecting a central stream of nely' divided fuel downwardly through said chamber and defiecting said stream upwardly at.. the bottom of the combustion chamber, and lprojecting air tangentially into the lower portion of the combustion chamber to set up a whirling motion in the gases therein and cause saidgases to travel upwardly ,through the combustion chamber in an annular whirling column surrounding said first mentioned downward stream.

.3. In combination, annular boiler heating surfaces, a combustion chamber enclosed thereby, means dis osed adjacent one end of said combustion c amberl for projecting a stream of finely divided fuel centrally therethrough and means adjacent the opposite end of'said chamber for setting up a- Whirl in the gases at such last mentioned end of the combustion cha'mber, said combustion chamber having one or more exhaust openings located 'adjacent the first mentioned end thereof.v

4. In combination, annular boiler'heating surfaces running substantially. vertically, a f

combustion chamber enclosed thereby, means!l associated with oneend of said combustion chamber n for projecting longitudinally through said chamber a central stream of finely divided fuel, means for admitting air tangentially of'the chamber adjacent the opposite end` thereof, said chamber having one or more exhaust openings locatedad-- jacent its first mentioned end.

5. The method of operating a boiler having a 'combustion chamber with boiler heating surfacesiadjacent the same which comprises projecting a stream of finely divided fuel into said chamber to burn the more readily combustible-fuel particles, maintainingy a fire bed beneath said combustion chamber toreceive other fuel particles, passing Aprimary air throu h the firebed to form producer ygas therefgrom, feeding the gases formed in said fire bed to said chamber, and introducing secondary air into said chamber tocomplete the combustion of said g'ases.

6. The method of operating a boiler having a combustion chamber with boiler.l heating surfaces adjacent the same, which comprises .projecting a central stream of finely divided fuel through said chamber, maintaining a fire bed beneath said chamber to receive fuel particles passing downwardly therefrom and forming producer gas from such particles,. and passing the gases produced from said fuel back through said chamber in the form of an annular column surrounding said first mentioned stream.

7 The method ofoperating a boiler having a combustion chamber with boiler heating surfaces adjacent the same, which comprises projecting a central stream of finely divided fuel through said chamber, maintaining a re bed beneath said chamber to receive fuel particles passing downwardly therefrom and forming producer gas fromsuch particles,

i and introducing secondary air into said chamber to complete the combustion of the producer g'as formed as aforesaid, and producing an annular column o'f gases surrounding said first mentioned stream. l

The method of operating a boiler having acombustion'chamber with boiler heating surfaces adjacent the same, which comprises' rojecting nely divided-fuel into saidcham er,

maintaining a fire bed beneath said chamber y to receive fuel particles therefrom, agitating.

said rebed from beneath and' removing ash l therefrom substantially uniformly to form a substantially uniform grade of producer gas therefrom and mixing secondary air with said producer gas in said combustion chamber in substantially proper proportions to complete the combustion of such gas adjacent the boiler heating surfaces.

9. In combinat1on,`annu lar boiler heating surfaces, a combustlon chamber enclosed,

thereby, means for admitting fuel adjacent the upper part of the combustion chamber,

means for supporting a bed of fuel adjacent4 the bottom of the combustion' chamber, fand .an up and outstroking agitating member rotatable with regard to the fuel bed andposiioned to operate. in the lower part of the fuel ed. o 10. In combination, annular'boiler heating 4 surfaces, a combustion chamber enclosed thereby, means for admitting fuel adjacent -the upper part'n of the combustion chamber,

means for supporting'a-bed of -fuel adjacent the bottom of the combustion chamber,and anv up and outstroking agitating member rotatable with regard to the fuel bed andpositioned to operate in the lower part ofthe fuel bed, together with means for 'admitting secondary air' to said chamber somewhat above the level of said fuel bed.

11. In combination, annular boiler heating surfaces, a combustion 'chambernclosed thereby, a grate disposed beneathsaid combustion chamber, an agitating member locatf ed over said grate and rotatable relative thereto, means for feeding inely'divided fuel into the upper portion of saidl combustion'chamber, and means for admittingl secondary air into the lower portion of said combustion chamber.

12. I n combination, annular boilerv heating surfaces, `a combustion 'chamber enclosed thereby, a grate disposed beneath said combustion chamber, an iagitating member located ovei said grate and rotatable relative thereto, means .for feeding finely divided fuel into the upper portion of said combustion-chamber, and' means for admitting secondary air into the lower portion of said combustion chamber, means being provided whereby the effective size of the grate openings as vregards ash removal may be adjusted, l

' 13. In combinatlon, boiler heating surfaces, a combustion chamber enclosed thereby, said heating surfaces also forming a heated gas passageway surrounding said combustion chamber, means for admitting nely divided fuel at the top of the combustion chamber and means for maintaining a fire bed at the bot tom of the combustion chamber wherein the boiler heating means for mechanically conditioning said bed of fuel,

15; In combination, annular boiler heating surfaces, a combustion chamber enclosedA thereby, a grate disposed beneath said combustion chamber, means -for mechanically f conditioning the fuel bed supported bysaid. grate, means for feeding finely divided fuel into the `upper portion'of said combustion chamber and means for admitting secondary air into the lower portion of said combustion chamber.

16. The method of burning finely divifded uei fuel,vwhich consists in projecting sai d\ into a combustion chamber, allowing the /.coarser particles to settle to the bottom of 4 said chamber and frm a relatively deep fuelbed thereon, generating producer gas from said fuel bed and burning said gas and the remainder of said fuel in said chamber.

v17. Method of burning inely divided fuel which consists in projectinglsaid fuel into a. combustion chamber, separating the finer particles from the coarser,- assing the finer particlesI while burning sus particles, forming producer gas therefrom and burning said gaswith'said finer particles.

18. yA boiler having heat exchange surfaces disposed contiguous tov .a 'combustion chamber, meansfor feedin a fire bed located in t chamber,means for forming producer gas of fuel downwardly onto. e lower portion of said stantially twice through said chamber, collecting said coarser substantially uniform quality in said fireb'ed,

and means for supplying. secondary air with-I in said chamber-to the producer gas 4so formed to burn the latter in said chamber. 19, The method of heating boilers which comprises feeding fuel downwardly through a chamber having heat exchange surfaces disposed contiguous thereto, maintaining substantially uniform producer gas making conditions in the fuel bed thus formed in the lower part of said chamber, admitting air to the fuel bed and thereby forming producer gas of. substantially uniform quality, and mixing secondary air with said producer gas in said chamber to complete the combustion Y thereof.

' burn the latter.

21. A boiler having heat exchange surfaces disposed .contiguous to a combustion chamber, means for feeding fuel to a fire bed located in the lower portion of said chamber, means for forming producer gas of substantially uniform quallty in said irebed comprising. an up stroking agitating member working in the bottom portion of the rebed and adapted to cause a vertical undulating A movement therein, and means for supplying secondary air within said chamber' to the producer as so formed to burn the latter in said cham er.

22. Incombination, a vertically disposed combustion chamber, boiler heating surfaces.

adjacent thereto, cylindrical rebed enclosing walls disposed beneath said chamber adapted A to hold a deep rebed suitable for the generation of producer gas, means operating concentrically in. the iirebed forl agitating the same, and means for forming a stratum of secondary air across said `combustion chamber just above the irebed.

23. In combination, 'boiler heating exchange'surfaces and a combustion chamber adjacent thereto, means for maintaining a gas producing irebed at'the bottom of said chamber and means for interposing a stratum of secondary air in the path of the gases arising from said iirebcd. y

'24. In combination, boiler heating exchange surfaces and a'combustion chamber v adjacent thereto. means for maintaining a gas producing irebed at the bottom of said chamber, means for interposing a stratum of secondary air in the path of the gases rising fromy said rebed andmeans for mechanically agitating the firebed.

25. In combination, a cylindrical combus tion chamber and boiler 'heat exchange surfaces enclosing the same, cylindrical firebed enclosing walls disposed beneath and coaxially with said chamber, means operating symmetrically with respectto the axis of said chamber for feeding fuel to the ircbed,

an agitating member rotating about the axis of said chamber inlthe firebed, means for admitting secondary airto the gases rising from the firebed, also acting symmetrically with regard to the axis of said chamber, means beneath said agitating member for discharging ashes symmetrically from the {irebed and admitting air evenly thereto, and means for withdrawing the gases of combustion symmetrically from said chamber.

In testimony that I claim the foregoing, I havehereunto set my hand this 24 day of July, 1926.

WILLIAM B@ CHAPMAN. 

